NEW YORK (AP) _ AT&T Corp. has been working for three days to re-establish contact with an important communications broadcast satellite that it was about to sell as part of a multimillion-dollar package.

Telstar 401, which carried TV signals for major customers including ABC, Fox and PBS, as well as telephone and computer data, stopped working Saturday and still wasn't back in service today.

Most customers' signals were quickly rerouted and no network was forced off the air by the outage.

``We still haven't determined the cause,'' said Mike Granieri, an AT&T spokesman. ``And until you determine the cause you can't put a fix on it _ or even know if there is a fix.''

Loral Space & Communications Ltd. agreed in September to buy AT&T's Skynet Satellite Services, which includes Telstar 401, for $712.5 million. The deal was expected to be completed in the first quarter of this year.

Jeanette Clonan, a Loral spokeswoman, said it was too early to speculate on how the satellite's failure might affect the sale.

Telstar 401 was one of two fully functioning Skynet satellites. One older Telstar was in only limited use.

Granieri confirmed that Telstar 401 was insured but would not give specifics.

It costs about $200 million to build, insure and launch satellites like the Telstar series. There are already plans to launch Telstar 5 this summer and two others in the future.

Loral Space, the company left over when Lockheed Martin Corp. bought Loral Corp.'s defense businesses, is involved in a host of satellite ventures.